Plzz do this

Dear student, Since each bacterial cell divides in 3 minutes in other words the number of cells get doubled every 3 minutes. We also know from the question that the cup gets filled in one hour. This means that cup was half filled in 60-3 = 57 minutes. Thus, cup was one fourth filled in 57-3= 54 minutes. Hence the answer is 54 minutes. Regards.